Various methods and apparatus exist for shielding or protecting potential targets, including surface vehicles, target, gun emplacements, ships, troop concentrations, and the like from projectiles.
One such protective apparatus uses devices containing emitter tubes to ward off threat projectiles. The devices are mounted in various locations on an exterior of a plane, normally. Each device heats an emitter tube to high temperatures, sometimes in the vicinity of 750 Kelvin. Once heated, the emitter tube begins to decay, emitting photons in the process. FIG. 1 is a graph of an example of the spectral radiant emissions from an emitter tube heated to a temperature of 750 Kelvin.
Threat projectiles are generally designed to seek emissions typical to targets. Typical target emissions include photons of 2–5 microns wavelength, some of which is quickly absorbed in the atmosphere, but some of which is not. Threat projectiles can be designed to seek out those photon emission wavelengths that are typical to targets and that are not typically quickly absorbed into the atmosphere.
The emissions from the heated emitter tubes tend to cloud the target, sometimes blinding the threat projectile from its target. FIG. 2 is an exemplary embodiment of a target 10 protected by emitter photon emissions. Surrounding the target 10 is a “zone of protection” 12 created by the emitter photon emissions. A threat missile fired into the “zone of protection” 12 will have its heat sensor, which is attempting to sense the photon emission from the target propulsion system, clouded by the emitter photon emissions and will typically fail to hit its target. Toward the rear of the target 10, in this embodiment, is the target propulsion system 14, the source of the photon emissions for targets. One of the limitations of the emitter tubes is that they fail to emit sufficient photons in the wavelengths sought by the threat projectiles to blind the projectiles at the target propulsion system 14. In other words, the “zone of protection” 12 does not extend to the location of the target propulsion system 14. As a result, a threat projectile fired from behind the target 10 may strike the target 10 without ever passing into the “zone of protection” 12. This problem is one of several encountered using the emitter tube system.
Another problem with the emitter tube system is robustness. The emitter tubes will produce photons in sufficient number for a short time period while operating at required levels. After this period of time passes, the emitter tubes need to be replaced, which typically requires the target to be on the ground. Most targets using this system will discard emitter tubes after a the period above minus a margin period in part because an target that requires a “zone of protection” does not want to have the emitter tubes expire while the target is airborne. A target defense system is needed that does not require such frequent maintenance.
Another problem with the emitter tube system is efficiency. Threat projectiles are typically targeting specific bands of photon wavelength emission. The wavelengths of these bands, known as “threat bands”, are all between 1.5 and 5 microns. However, combined, the threat bands are approximately 2 microns wide. As can be seen from FIG. 1, typical effective wavelength emissions from the emitter tube system are approximately 7–8 microns wide. Therefore, most of the emissions from the emitter tubes are not impacting the bands of photon wavelength emissions sought by the threat projectiles and those emissions are being wasted. Preferably, a target defense system could be designed that wasted less energy.
Another problem with the emitter tube system is scalability. FIG. 3 is a graph of an example of the spectral radiant emissions from an emitter tube heated at a temperature above 750 Kelvin. As can be seen by FIG. 3, as compared to FIG. 1, the peak of the curve shifts to the left as the temperature of emitter tube increases. A band of some interest in projectile defense is the approximately 2–5 micron wavelength band. As can be seen by FIG. 3, as compared to FIG. 1, even as more power is used to heat the emitter tube to a higher temperature, the photon emissions in the 2–5 micron wavelength band decrease. Ideally a projectile defense system would increase photon emissions in the 2–5 micron wavelength band as power to the system is increased (i.e., be scalable).
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.